*From where in the cosmos exactly? Who 'beamed' us here? For that matter, what the heck is a 'beam?'*
From everywhere in the Cosmos [Q]. There are all kind of layers in the Cosmos with all kind of Beings (in Energy) there. I understand it is hard to get for you.
*Then what is the purpose of having a brain? Oops... I may be asking the wrong person.*
The purpose of having a brain is to conceive your mind [Q]. You, of all people here, should have to know that the brain exists out of organic, thus Earth-bound 'material. I understand it is difficult to comprehend for you.
*Then wouldn't they no longer constitute being 'memories?'*
Oh yes, they would! Most humans don't remember the memories of a former life-time. They are there though. You go on in your next life-time, dealing with the memories, or experiences, you had in a former life-time. In the life-time you live now, you have to go further and learn more about living in harmony with Earth, Nature and the Cosmos. Did you live your former life in a real 'bad' way, you have to deal with the consequences. So, good chance you start with nothing and learn to look at life with a different view. The memories remain, in the background. You cannot realise it, they are there. I understand this is also difficult to get for you...